Magnetism and magnetocaloric effects in Ni_(50)Mn_(35-x)Co_xIn_(15) Heusler alloys

摘要

The effects of the partial substitution of Mn by Co on the magnetic, magnetoelastic, and magnetocaloric properties of Ni_(50)Mn_(35)In_(15) Heusler alloys were studied using x-ray diffraction, temperature and field dependences of the magnetization [M(T,H)], and strain gauge techniques. It was observed that the presence of ≈3% Co atoms in Mn sites strongly affected the magnetic and magnetoelastic behaviors of Ni_(50)Mn_(35)In_(15) . At H = 5 T, a maximum magnetoelastic strain of ≈0.6% was observed for Ni_(50)Mn_(35)ln_(15) . It was found that Co substituted into the Mn position does not affect the △S_M in the vicinity of the second order transitions (SOTs), however △S_M near the first order transitions (FOTs) it slightly decreases. The net refrigeration capacities in the vicinity of both the FOT and SOT were found to significantly increase by introducing Co into Mn sites. The net refrigeration capacity in the vicinity of the FOT and SOT was found to be 167 J/kg (T =277-293 K) and 229 J/kg (T=305-354 K), respectively, at a magnetizing field of 5 T. These values of the magnetocaloric parameters are comparable to that of the largest values reported for metallic magnets near room temperature.